Computerized modeling of electronic devices allows for inexpensive and efficient computerized design of electric circuits and systems. A discrete electronic device such as a bipolar transistor requires a large number of parameters to accurately model its operational characteristics. For example, a typical bipolar transistor using the SPICE modeling system requires on the order of thirty parameters to sufficiently specify its operational characteristics.
Once the parameters of an electronic device have been calculated so that the electronic device can be modeled, computer aided design systems can efficiently design circuits using the electronic device and use the calculated parameters to accurately predict the operational characteristics of the circuit comprising the device. In order to calculate the thirty or so parameters used to model an electronic device such as a bipolar transistor, the device is tested at various points in its operating spectrum to construct a data set of measured data values. A first guess is then made at the values for the modeling parameters of the device. An objective function is then calculated which represents a summation of the error between the measured and calculated parameters for all of the parameters necessary for modeling the device. Using an iterative process, the parameters are changed to minimize the value of the objective function. When the objective function is minimized, the values for the modeling parameters represent the closest approximation of the modeled parameters to the actual measured parameters.
For a variety of reasons, the modeling parameters are given minimum or maximum limiting values. These limiting values aid in the efficient minimization of the objection function as well as embodying certain physical constraints of the devices and their corresponding parameters. In some systems, the minimization of the objective function is slowed considerably when the minimization process crosses one of these arbitrary boundaries. Accordingly, the need has arisen for an optimization system which can react to the presence of an arbitrary maximum or minimum value of a modeling parameter and efficiently proceed with the minimization of the objective function to quickly and efficiently arrive at the correct set of modeling parameters for a given device.